Beijing Advanced Innovation Center for Tree Breeding By Molecular Design, Beijing Key Laboratory of Ornamental Plants Germplasm Innovation & Molecular Breeding, National Engineering Research Center for Floriculture, Beijing Laboratory of Urban and Rural Ecological Environment, Engineering Research Center of Landscape Environment of Ministry of Education, Key Laboratory of Genetics and Breeding in Forest Trees and Ornamental Plants of Ministry of Education, School of Landscape Architecture, Beijing Forestry University, Beijing, 100083, China.
Sci Rep. 2021 Jan 29;11(1):2675. doi: 10.1038/s41598-021-81892-3.
Prunus mume (also known as Mei) is an important ornamental plant that is popular with Asians. The weeping trait in P. mume has attracted the attention of researchers for its high ornamental value. However, the formation of the weeping trait of woody plants is a complex process and the molecular basis of weeping stem development is unclear. Here, the morphological and histochemical characteristics and transcriptome profiles of upright and weeping stems from P. mume were studied. Significant alterations in the histochemical characteristics of upright and weeping stems were observed, and the absence of phloem fibres and less xylem in weeping stems might be responsible for their inability to resist gravity and to grow downward. Transcriptome analysis showed that differentially expressed genes (DEGs) were enriched in phenylpropanoid biosynthesis and phytohormone signal transduction pathways. To investigate the differential responses to hormones, upright and weeping stems were treated with IAA (auxin) and GA (gibberellin A3), respectively, and the results revealed that weeping stems had a weaker IAA response ability and reduced upward bending angles than upright stems. On the contrary, weeping stems had increased upward bending angles than upright stems with GA treatment. Compared to upright stems, interestingly, DEGs associated with diterpenoid biosynthesis and phenylpropanoid biosynthesis were significantly enriched after being treated with IAA, and expression levels of genes associated with phenylpropanoid biosynthesis, ABC transporters, glycosylphosphatidylinositol (GPI)-anchor biosynthesis were altered after being treated with GA in weeping stems. Those results reveal that multiple molecular mechanisms regulate the formation of weeping trait in P. mume, which lays a theoretical foundation for the cultivation of new varieties.
青梅（Prunus mume），又称梅，是一种重要的观赏植物，在亚洲广受欢迎。其垂枝性状因其具有较高的观赏价值而引起了研究人员的关注。然而，木本植物的垂枝性状的形成是一个复杂的过程，其茎下垂发育的分子基础尚不清楚。本研究对青梅直立和垂枝的形态学和组织化学特征以及转录组谱进行了研究。观察到直立和垂枝组织化学特征的显著变化，垂枝中缺乏韧皮纤维和木质部较少，可能导致其无法抵抗重力并向下生长。转录组分析表明，差异表达基因（DEGs）在苯丙烷生物合成和植物激素信号转导途径中富集。为了研究激素的差异响应，分别用 IAA（生长素）和 GA（赤霉素 A3）处理直立和垂枝，结果表明，垂枝对 IAA 的响应能力较弱，向上弯曲角度比直立枝小。相反，用 GA 处理时，垂枝的向上弯曲角度比直立枝大。与直立枝相比，有趣的是，用 IAA 处理后，与二萜生物合成和苯丙烷生物合成相关的 DEGs 显著富集，而用 GA 处理后，与苯丙烷生物合成、ABC 转运蛋白、糖基磷脂酰肌醇（GPI）-锚生物合成相关的基因表达水平发生改变。这些结果表明，多种分子机制调控了青梅垂枝性状的形成，为培育新品种奠定了理论基础。
